title: Role of claudin species-specific dynamics in reconstitution and remodeling of the zonula occludens.
abstract: Tight-junction strands, which are organized into the beltlike cell-cell adhesive structure called the zonula occludens (TJ), create the paracellular permselective barrier in epithelial cells. The TJ is constructed on the basis of the zonula adherens (AJ) by polymerized claudins in a process mediated by ZO-1/2, but whether the 24 individual claudin family members play different roles at the TJ is unclear. Here we established a cell system for examining the polymerization of individual claudins in the presence of ZO-1/2 using an epithelial-like cell line, SF7, which lacked endogenous TJs and expressed no claudin but claudin-12 in immunofluorescence and real-time PCR assays. In stable SF7-derived lines, exogenous claudin-7, -14, or -19, but no other claudins, individually reconstituted TJs, each with a distinct TJ-strand pattern, as revealed by freeze-fracture analyses. Fluorescence recovery after photobleaching (FRAP) analyses of the claudin dynamics in these and other epithelial cells suggested that slow FRAP-recovery dynamics of claudins play a critical role in regulating their polymerization around AJs, which are loosely coupled with ZO-1/2, to form TJs. Furthermore, the distinct claudin stabilities in different cell types may help to understand how TJs regulate paracellular permeability by altering the paracellular flux and the paracellular ion permeability.
authors.affiliation: Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine Nuclear Dynamics Group, Graduate School of Frontier Biosciences, Osaka University, Osaka 565-0871, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Reitaro
authors.initials: R
authors.lastname: Tokumasu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kimura
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tsukita
mesh_terms: D022005:Adherens Junctions; D002460:Cell Line; D057167:Claudins; D004847:Epithelial Cells / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005614:Freeze Fracturing; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D038761:Photobleaching; D016133:Polymerase Chain Reaction; D058105:Polymerization; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
chemical_list: C508912:CLDN19 protein, human; C473255:CLDN7 protein, human; D057167:Claudins; D008565:Membrane Proteins; D010750:Phosphoproteins; C569042:TJP1 protein, human; C569046:TJP2 protein, human; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; C422064:claudin 14